1. Field of the Invention
An apparatus and method consistent with the present invention relate to a perpendicular magnetic recording head and, more particularly, to a perpendicular magnetic recording head having an improved shape of a main pole such that the perpendicular magnetic recording head has a minimum influence by a magnetic field on a track except for an object track of a recording medium that is to be recorded, thereby achieving high density recording, and a manufacturing method thereof.
2. Description of the Related Art
Magnetic recording may be roughly classified into longitudinal magnetic recording and perpendicular magnetic recording depending on information recording methods. The longitudinal magnetic recording records information using characteristics in that the magnetized direction of a magnetic layer is aligned in parallel to the surface of the magnetic layer, and the perpendicular magnetic recording records information using characteristic in that the magnetized direction of a magnetic layer is aligned perpendicularly to the surface of the magnetic layer. Therefore, the perpendicular magnetic recording has much greater advantages than the longitudinal magnetic recording in an aspect of recording density.
FIG. 1 is a view of a conventional perpendicular magnetic recording head. Referring to FIG. 1, the perpendicular magnetic recording head includes a perpendicular magnetic recording medium 10 (referred to as a recording medium), a recording head unit 100 which records information on the recording medium 10, and a read head unit 110 which reads information recorded on the recording medium 10.
The recording head unit 100 includes a main pole P1, a return yoke 105, and a coil C. The coil C generates a recording magnetic field in order to record information on the recording medium 10. The main pole P1 and the return yoke 105 constitute a magnetic path of the recording magnetic field generated from the coil C. Each of the main pole P1 and the return yoke 105 is formed of a magnetic material such as NiFe. Here, saturation magnetic flux density Bs is formed differently by controlling a constituent ratio of the magnetic material in each of the main pole P1 and the return yoke 105. A sub-yoke 101 is formed on a lateral side of the main pole P1. Also, the sub-yoke 101 constitutes a magnetic part together with the main pole P1.
The read head unit 110 includes a first shield layer S1, a second shield layer S2, and a read sensor 111 formed between the first and second shield layers S1 and S2. The first and second shield layers S1 and S2 prevent a magnetic field generated from a magnetic element around a predetermined region ARP of a selected track from reaching a read sensor 111 while information is read from the predetermined region ARP. The read sensor 111 may be at least one of a magnetoresistance (MR) device, a giant magnetoresistance (GMR) device, and a tunnel-magneto-resistance (TMR) device.
An air-bearing surface (ABS) is defined as a surface where the recording head unit 100 faces a recording layer 13 and is parallel to an X-Y plane.
A vertical component of a magnetic field applied from the main pole P1 and directed to the recording medium 10 magnetizes a magnetic domain of the recording layer 13 in order to record information. One unit magnetized in this manner is called a recording bit. As recording density increases, the size of the recording bit decreases.
The recording density is generally represented by areal density and expressed by the number of recording bits per 1 inch2. That is, to increase the areal density, both a length in a down-track direction and a length in a cross-track direction of a recording bit should be reduced.
The length in the down-track direction is determined by the movement speed of the recording medium 10 and the frequency of a recording current. The length in the cross-track direction depends on the shape of the main pole P1 including the length of the main pole P1 in a Y-direction. Therefore, it is difficult to design such that the length continues to decrease as the recording density increases, and the main pole P1 should have a shape that does not influence an adjacent track to achieve stable recording performance.